Safety device for punch-presses.



G. H. HAMlLTON.

SAFETY DEVICE FOR PUNCH PRESSES.

APPLICATION mm JAN. 3. i916.

Patented May 23,1916.

2 SHEETS-rSHEET-l lnl/e/vfor I Geol qg d Ham/Q47 THE COLUMBIA PLANOGRAPH60-, WASKINGTDN. n. c.

a. H. HAMiLTONf SAFETY DEVICE FOR PUNCH PRESSES.

APPLICATION FILED MN. 3. 1915.

1,1 84 446. Patented May 23, 1916.

2 SHEETSSHEET 2.

GEORGE H. HAMILTON, 0F GRAND RAPIDS, MICHIGAN.

SAFETY DEVICE FOR PUNCH-PRESSES.

Specification of Letters Patent.

Patented May 23, 1916.

Application filed January 3, 1916. Serial No. 69,883.

To all whom it may concern:

Be it known that I, Gnonon H. HAMiLTON, a citizen of the United Statesof America residing at Grand Rapids, in the county of Kent and State ofMichigan, have invented. certain new and useful Improvements in SafetyDevices for Punch-Presses; and I do hereby declare the following to be afull, clear, and exact description of the invention, such as will enableothers skilled in the art to which it appertains to make and use thesame.

This invention relates to a safety appliance or device especiallyadapted for use in connection with power operated punch presses.

In a punch press the punching ram is mounted for vertical movements andmoves toward and from the work operated upon, and in many instancesafter a piece of material has been operated upon the momentum of themoving parts of the press causes the ram to make an extra stroke orstrokes after it should have stopped, and the operator, not expectingsuch movements on the part of the machine, will, in many cases, haveintroduced his hands under the ram and be caught thereby, accidents ofthis nature occurring very frequently.

It is the object and purpose of this invention to provide a mechanismwhich can be attached to punch presses of ordinary construction andwhich will serve to positively stop any extra movement of the ram overand above that desired, it being absolutely necessary for each downwardmovement of the ram that the operator perform an opera tion initiatoryto the operation of the ram, otherwise it will not work at all. To thisend I have provided the structure shown in the accompanying drawingswhich is de signed to accomplish the primary object of the inventiondescribed together with many other minor and subsidiary objects whichhave not been specifically enumerated but which will appear asunderstanding is had of the mechanismshown in the drawings.

Figure 1 is an enlarged section and plan taken substantially on the line11 of Fig. 4. Fig. 2 is a side elevation drawn to the same scale as Fig.1 of a detail of the mechanism. v Fig. 3 is a plan view showing mysafety appliance applied to the punch press. Fig. 4 is a side elevationthereof; Figs. 5, 6 and 8 are side elevations of details of themechanism; and Fig. 7 is a plan view of a detail of said mechanism.

Like reference characters refer to like parts throughout the severalviews of the drawings.

The punch press to which this device is applied is of ordinaryconstruction having a suitable base from which project upwardly housingsupports 1, one only of said supports being shown in the drawings.Suitable guides 2 are formed adjacent the front of the housing supportsbetween which the ram 3 is mounted for vertical reciprocatory movements.A table 1: is supported by the base directly below the ram 011 which asuitable stationary die 5 may be secured, the companion die 6 beingattaehed to the lower end of the ram 3. A shaft 7 is mounted at theupper end of and between the housings 1 having a wheel 8 secured theretoagainst which a stop element 9 engages, this element being mounted atthe end of a lever 10 pivotally mounted between its ends at 11 to a studprojecting from a side of one of the housings 1. A weight 12 isadjustably mounted on the free end of lever 10 serving normally to bringthe part 9 in engagement with the wheel 8. This may be any ordinaryconstruction of any punch press of usual and well known design. The part9 engaging with the wheel 8 usually has a projection adapted to insertin an opening in the wheel 8 so that when it engages with the wheel 8the tendency is to stop the punch press at a certain particular portionof the movement of the ram, the power driving the press cutting out atthe same time. Inasmuch as the driving construction is not any featureof the present invention it is not shown in detail, except what isnecessary to illustrate its connection with my invention.

A foot lever 13 is pivotally mounted at the lower end of the base of thepunch press and adjacent the rear thereof. A rod 1 f connected at itslower end between the ends of the foot lever 13 extends upwardly to therear and at its upper end is secured to the rear end of an arm 15loosely mounted on a stud 16 which projects outwardly from the side ofthe support 1. A strong coil spring 17 attached to this arm and to thesupport 1 normally tends to elevate it also elevating the foot lever 13as will be understood. On the stud 16 are loosely mounted a star Wheel18, and a ratchet wheel 19 side by side, these two 'wheels beingsuitably connected together so as to move in unison. A pawl 20 ispivotally mounted on arm 15 and is spring operated to engage with theratchet wheel 19.

A lever 21 is pivotally mounted between its ends to a stud projectingoutwardly from the side of support 1 at its rear end being formed withan upwardly extending pointed projection 22 adapted to engage betweenany two consecutive projections of the star wheel 18. Below the forwardend of this lever an idle pulley 23 is mounted and a flexible connectionsecured to the lever 21 passes around this wheel extending upwardly andconnected at its upper end to the lever 10 in front of its pivot 11.

A bell crank lever having a rearwardly projecting substantiallyhorizontal arm 25 and a vertical arm 26 is pivotally mounted as shown toa stud 27 projecting from the support 1. The free end of this levercarries a weight 28 adjustable thereon and between the forward end oflever 21 and the arm 25 a tie 29 is positioned. In front of the bellcrank lever and of the housing 1 and above the rear end of the base 4 alever 30 is pivotally mounted between its ends, a link 31 connecting oneend thereof with the upper end of the arm 26 heretofore de scribed. Atthe opposite end of lever 30 a clamping member 32 is rigidly securedprojecting forward and having a companion clamping member 33 betweenwhich and the member 31 a vertical post 34: is secured. On the rear sideof the housing support 1 a lever 35 is pivotally mounted between itsends, one portion of which extends back of the pivot and carriesadjustably thereon a weight 36 while its opposite end is slightlywidened and formed with an upwardly inclined part 37 at its upper edgeforming a hook with an abrupt shoulder 38 a distance back of the frontend as shown in Fig. 5. A notclr39 is made on the front edge of thelever 30 directly above the forward end of the member 35.

A rod 10 extends rearwardly from and is supported by the ram 3 beingformed with a sleeve at its rear end in which is mount ed a vertical rod41, the lower end of which in the downward movement of the ram enters anotch 42 in the side of member 35, thereby causing the member 35 to turnabout its pivot depressing its forward end and elevating the weight 36.

In the operation of the mechanism, in order to start the punch press theoperator must step on the end of foot lever 13 depressing it. When thisoccurs arm 15 is rotated about its pivotal mount and as pawl 20 engageswith the ratchet wheel 19 it will be evident that the star wheel willhave a partial revolution sufficient that one of the projections ridingover the part 22 of lever 21 serves to elevate the forward end of lever21 pulling on the flexible connection 24 and removing the member 9 fromthe part 8 thus freeing the mechanism for movement and, as is common inpunch press constructions, connecting the power with the shaft 7 for theoperation of the punch press. At the same time the arm 25 of the bellcrank lever is elevated, the upper end of arm 26 being thrown forward tooperate the lever 30 to dotted line position shown in Fig. 1 or to sucha position that the hook at 38 may pass into the notch at 39 and holdthe post 3 1 in rear position out from under the ram 3. WVhen the starwheel is rotated a partial revolution as the lever 15 is depressed pawl20 rides against a pin 13 which projects outwardly from the housingsupport 1 causing the pawl to disengage.

from the ratchet 18. And it will be apparcut that the influence of theweight 28 will cause the projection 22 to always seat between two of theprojections on the star wheel immediatelv after the lever 13 has beendepressed, and the machine started in operation, the efiect of whichwill be to permit lever 21 to occupy its original position with themember 9 engaging against the wheel 8. Accordingly when the shaft 7 hasmade one revolution, the part 9 engaging therewith will tend to stop itand ordinarily if this stopping of the device occurs every time, noadditional safety appliance would be needed. In practice, however, themomentum which the moving parts of the punch press have is so great thatany projection on the part 9 extending into a depression in the part 8is often broken or rendered useless, the shaft thereupon continuing itsrevolution, elevating the ram 3 and again carrying it down for furtheroperation. In my device with the first downward movement of the ram 3,after an operation begins, rod 41 engages with lever 35 depressing theforward end thereof and disengaging it from lever 30 so that when theram is elevated after the completion of one downward stroke, lever 30 isreleased, the weight 28 immediately throwing the post 34 under the ramsothat when a second downward movement of the ram is attempted itstrikes against the post and is stopped. Accordingly after eachoperation of the ram it is necessary to depress the foot lever 13 beforeit will again operate and it is impossible to have an accidentaldownward movement of the ram except after a depression of foot lever bythe operator.

Many changes in minor detail of construction will occur to othersskilled in the art and accordingly I do not wish to be limited to theexact specific details of structure shown.

The appended claims define the invention and all modifications ofstructure falling within their scope are to be considered ascomprehended by my invention.

1. In combination with a support, a vertically movable ram mounted onthe support, means to operate the ram, a foot-lever pivotally mounted onthe support, a post normally positioned under the ram, means operable bythe foot-lever for withdrawing the post and simultaneously freeing theram operating means, means for holding the post back of the ram duringits down ward stroke, and means on the ram for engaging and operatingsaid holding means on said downward stroke of the ram to free the postfor return to normal position.

2. In combination, a support, a ram mounted for vertical reciprocatorymovements thereon, means to operate the ram normally held in restraint,a lever pivotally mounted on the support, a post mounted on the supportand movable back and forth with respect to the ram, means connected withthe post for normally locating it in forward position under the ram andmeans operable by the lever for withdrawing the post to the rearposition and simultaneously freeing the ram for one reciprocation,substantially as described.

3. In a punch press, a ram mounted for vertical reciprocating movements,means to operate the ram, a post movably mounted on the punch pressadjacent the ram and normally located thereunder, a lever, meansoperable by the lever for moving the post from under the ram, a catchfor holding the post in withdrawn position, means sinniltaneouslyoperated by the lever for freeing the ram for reciprocation, and meanson the ram engaging with the catch for freeing the post to return tonormal position on downward movement of the ram.

at. An attachment for punch presses comprised of a lever pivotallyconnected to the support for the press, a stud projecting from saidsupport, a ratchet and star wheel secured together and loosely mountedon the stud, an arm loosely mounted on the stud, a pawl on the armengaging the ratchet wheel, a connection between the lever and arm, apin extending from said support in front of the pawl, a lever pivotallymounted between its ends on the support and provided with a projectionengaging the star wheel, a bell crank lever mounted on the support andhaving a weighted arm, a tie between said arm and the free end of thefirst lever, a notched lever mounted on and transversely of-the support,a connection between the bell crank lever and one end of the notchedlever, a post attached to the opposite end of the notched lever, a latchlever pivotally mounted below said notched lever and having one endweighted and the opposite end hooked to enter the notch of the notchedlever in one position thereof, a ram vertically reciprocable under whichthe post is adapted to locate, and a rod on the ram directly above thelatch lever for e11- gaging therewith on downward movement of the ram.

5. In combination, with a support, a power driven ram mounted on thesupport for vertical reciprocatory movements, means to operate the .ram,a table below the ram, a device normally locating between the lower endof the ram and table to stop downward movement of the ram, means forsimultaneously withdrawing said stopping device and freeing the ram formovement, means to hold said stopping device away from the ram while itmakes one downward stroke, and means for automatically releasing saidholding means to permit the stop device to take its normal positionafter one downward stroke of said ram.

6. In combination, with a power punch press, a safety appliance attachedthereto including a stop device adapted to interpose between the am andthe table of the press, a lever, means associated therewith for placingthe press in operation, and additional means associated with andoperated by the lever for withdrawing the stop device to inoperativeposition while the ram makes one operation, substantially as described.

In testimony whereof I affix my signature.

GEORGE H. HAMILTON.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents. Washington, D. 0.

